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Income Taxes (Reconciliation of Statutory Taxes to Effective Taxes) (Details) - USD ($) $ in Millions | 12 Months Ended
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Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017
Income Tax Disclosure [Abstract] |  |  |
Tax at U.S. federal statutory income tax rate of 35% | $ 17.2 | $ 23.4 | $ 27.5
Adjustments to reconcile to income tax expense (benefit): |  |  |
Federal Valuation Allowance | 1.3 | 0.5 | 0.4
State income taxes, net of federal benefit | 3.2 | 4.8 | 2.7
Domestic production activities deduction | 0.0 | (2.4) | (4.5)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount | 0.0 | (42.5) | (0.4)
Federal transition tax | (0.6) | 7.5 | 0.0
Uncertain tax positions | (1.4) | 0.0 | 0.0
Basis difference in foreign investment | (1.1) | 0.0 | 0.0
Excess tax benefits related to stock compensation | (0.3) | (0.6) | (2.1)
Tax Credits | (1.8) | (1.7) | (1.4)
Other nondeductible expenses | 1.3 | 0.5 | 0.6
Foreign income taxes | 0.1 | 0.0 | 0.3
Nondeductible compensation | 0.3 | 0.2 | 0.5
Other income tax | 0.1 | 0.4 | 0.6
Income tax expense (benefit) | $ 18.3 | $ (9.9) | $ 24.2

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